The present invention relates to an image display device which utilizes an emission of electrons into a vacuum to produce a display; and, more particularly, the invention relates to an image display device of the type described which exhibits high brightness and excellent image reproducibility by enhancing the electron emission characteristics of the electrons emitted from the electron sources and the focusing characteristics of the electron beams.
As an image display device which exhibits a high brightness and high definition, color cathode ray tubes have been popularly used conventionally up to now. However, along with a recent demand for the provision of higher quality images in information processing equipment or in television broadcasting, the demand for planar displays (panel displays) which are light in weight and require a small space, while exhibiting a high brightness and high definition has been increasing.
As typical examples, liquid crystal display devices, plasma display devices and the like have been put into practice. Further, as display devices which can realize higher brightness, various kinds of panel-type display devices, including a display device which utilizes an emission of electrons from electron sources into a vacuum space (hereinafter referred to as an electron emission type display device or a field emission type display device) and an organic EL display device, which is characterized by low power consumption, have been commercialized.
Among such panel type display devices, such as the above-mentioned field emission type display device, there are a display device having an electron emission structure, which was proposed by C. A. Spindt et al. (see U.S Patent Specification 3453478, Japanese Unexamined Patent Publication 2000-21305, for example), a display device having an electron emission structure of a metal-insulator-metal (MIM) type, a display device having an electron emission structure which utilizes an electron emission phenomenon based on a quantum theory tunneling effect (also referred to as “surface conduction type electron source, see Japanese Unexamined Patent Publication 2000-21305), and a display device which utilizes an electron emission phenomenon having a diamond film, a graphite film and carbon nanotubes and the like, for example.
The above-mentioned field emission type display device is configured such that the display device includes a back substrate, on which cathode lines having field emission type electron sources are formed on inner surfaces thereof along with control electrodes, and a face substrate, on which forms anodes and phosphor layers are formed on an inner surface thereof which faces the back substrate. The back substrate and the face substrate are laminated to each other with a sealing frame interposed between inner peripheral portions thereof to form a space in a vacuum state therebetween. Further, there is also a known structure in which, to maintain a desired distance between the back substrate and the face substrate at a given value, distance holding members are provided between the back substrate and the face substrate. Here, this type of device is described in Japanese Unexamined Patent Publication Hei10 (1998)-134701, Japanese Unexamined Patent Publication 2000-306508 and the like.